Tests to be done prior to Pregnancy
ISSUES TO CONSIDER BEFORE PREGNANCYIn an ideal world patients would receive facts about pregnancy, its risks to the mother, and the chances of genetic or congenital disorders prior to conception. Such pre-pregnancy planning would reduce the shock and panic of high-risk patients when they discover problems at the last moment. This is a window of opportunity for medical practitioners and patients to resolve issues before they become problems.
Family History
Although sometimes this may seem an invasion of privacy, obtaining information about the outcome of a relation’s pregnancy may provide important information for the management of the next pregnancy. If the patient has had a previous pregnancy loss, all information however trivial may be helpful. Such things as autopsy reports, although possibly inconclusive and not diagnostic may exclude some other conditions.
Previous pregnancies especially previous fetal loss, congenital abnormalities or stillbirth should be investigated.
Occur in approximately 1 in 700 pregnancies in a Caucasian population. However the vast majority of babies born are to couples with no reason to suspect they are at any increased risk. Folic acid prior to pregnancy will reduce the recurrence risk by at least half.
In some parts of the world, consanguineous marriages are very common. Figures of up to 35% are quoted for some regions. They are favoured for a variety of cultural reasons. In an immigrant population, the incidence may be even higher. Geographical isolation may enhance these group loyalties. These couples may benefit from Genetic counselling even where there is no family history of any congenital abnormalities.
Ethnicity
There are some genetic disorders more common in certain populations than others. These are simple to investigate either as an individual or a couple. Genetic counselling would be recommended for any couples who are carriers of these conditions.
The incidence of carrier status in a Caucasian population is 1 in 25. In 1997 the NIH (United States National institutes of Health) recommended testing for carrier status in individuals with a family history of the disease and partners of people with cystic fibrosis. At present in Australia this is available for DeltaF508 (the commonest mutation) and for a panel of eight others which account collectively for 85% of the known mutations.
Carrier testing can take a considerable time (at least 6 weeks) and is best done prior to conception so that appropriate advice about the management of the pregnancy and prenatal diagnostic procedure can be arranged.
Advanced Maternal Age (>35 at the time of delivery)
The increased risk of chromosomal disorders is well known. Many patients would benefit from genetic counselling prior to conception so they are aware of their options.
Maternal Counselling / Advice / Genetic Counselling
See the appropriate pages on the website. All women should be told to increase their folic acid intake, stop smoking and limit drinking.
Maternal Disease
These particular medical conditions (and their common treatments) can affect the fetus and the pregnancy. A specialist should be consulted before starting a pregnancy.
Mutation Testing
If there is any parental condition which may be diagnosed by such methods as DNA, the mutations involved (ideally from the affected family members) should be determined as early as possible to allow time for the mutations to be determined.
LIFESTYLE ISSUES
TERATOGENS
Infectious
- Rubella
- Toxoplasmosis
- Syphilis
- CMV
- Listeria
- HSV
- Varicella
- Parvovirus
- HIV
Physical
Radiation 2-10 rads, no concern, concern if receive btwn 2-4 weeks of gestation Avoid (LMP rule)
no association with Microwaves / VDU
Ultrasound
Heat anecdotal - NTD + severe IUGR
Exercise
Mechanical (intrauterine) - amniotic bands - oligohydramnios ;talipes - twins
Drugs + Chemical Agents
Maternal Metabolic + Genetic
Tests to be done prior to Pregnancy